[cond-expr] don't allow conditional as left value for the first stage

Lu Guanqun · Lu Guanqun · commit bf7daf0814ac · 2016-01-22T17:14:00.000Z
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
@@ -748,55 +748,37 @@ bool TypeChecker::visit(Conditional const& _conditional)
 {
 	expectType(_conditional.condition(), BoolType());
 
-	if (_conditional.annotation().lValueRequested)
-	{
-		requireLValue(_conditional.trueExpression());
-		requireLValue(_conditional.falseExpression());
-
-		TypePointer const& trueType = type(_conditional.trueExpression());
-		TypePointer const& falseType = type(_conditional.falseExpression());
+	_conditional.trueExpression().accept(*this);
+	_conditional.falseExpression().accept(*this);
 
-		// as a left value, we require exact match to prevent subtle conversion issues.
-		if (*trueType != *falseType)
-			typeError(
-					_conditional.location(),
-					"True expression's type " +
-					trueType->toString() +
-					" doesn't match false expression's type " +
-					falseType->toString() +
-					"."
-			);
+	TypePointer const& trueType = type(_conditional.trueExpression());
+	TypePointer const& falseType = type(_conditional.falseExpression());
 
-		_conditional.annotation().type = trueType;
-		_conditional.annotation().isLValue = true;
-	}
-	else
+	// we fake it as an equal operator, but any other comparison operator can work.
+	TypePointer commonType = trueType->binaryOperatorResult(Token::Equal, falseType);
+	if (!commonType)
 	{
-		_conditional.trueExpression().accept(*this);
-		_conditional.falseExpression().accept(*this);
+		typeError(
+				_conditional.location(),
+				"True expression's type " +
+				trueType->toString() +
+				" doesn't match false expression's type " +
+				falseType->toString() +
+				"."
+		);
+		// even we can't find a common type, we have to set a type here,
+		// otherwise the upper statement will not be able to check the type.
+		commonType = trueType;
+	}
 
-		TypePointer const& trueType = type(_conditional.trueExpression());
-		TypePointer const& falseType = type(_conditional.falseExpression());
+	_conditional.annotation().type = commonType;
 
-		// we fake it as an equal operator, but any other comparison operator can work.
-		TypePointer commonType = trueType->binaryOperatorResult(Token::Equal, falseType);
-		if (!commonType)
-		{
-			typeError(
-					_conditional.location(),
-					"True expression's type " +
-					trueType->toString() +
-					" doesn't match false expression's type " +
-					falseType->toString() +
-					"."
-			);
-			// even we can't find a common type, we have to set a type here,
-			// otherwise the upper statement will not be able to check the type.
-			commonType = trueType;
-		}
+	if (_conditional.annotation().lValueRequested)
+		typeError(
+				_conditional.location(),
+				"Conditional expression as left value is not supported yet."
+		);
 
-		_conditional.annotation().type = commonType;
-	}
 	return false;
 }
 
diff --git a/test/libsolidity/SolidityEndToEndTest.cpp b/test/libsolidity/SolidityEndToEndTest.cpp
@@ -128,22 +128,6 @@ BOOST_AUTO_TEST_CASE(conditional_expression_multiple)
 	BOOST_CHECK(callContractFunction("f(uint256)", u256(40)) == toBigEndian(u256(10)));
 }
 
-BOOST_AUTO_TEST_CASE(conditional_expression_as_left_value)
-{
-	char const* sourceCode = R"(
-		contract test {
-			function f(uint x) returns(uint d) {
-				uint y = 1;
-				uint z = 1;
-				(x > 10 ? y : z) = 3;
-				return y ** z;
- 			}
-		})";
-	compileAndRun(sourceCode);
-	BOOST_CHECK(callContractFunction("f(uint256)", u256(20)) == toBigEndian(u256(3)));
-	BOOST_CHECK(callContractFunction("f(uint256)", u256(5)) == toBigEndian(u256(1)));
-}
-
 BOOST_AUTO_TEST_CASE(conditional_expression_with_return_values)
 {
 	char const* sourceCode = R"(
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -2972,12 +2972,14 @@ BOOST_AUTO_TEST_CASE(invalid_different_types_for_conditional_expression)
 	BOOST_CHECK(expectError(text) == Error::Type::TypeError);
 }
 
-BOOST_AUTO_TEST_CASE(invalid_left_value_in_conditional_expression)
+BOOST_AUTO_TEST_CASE(left_value_in_conditional_expression_not_supported_yet)
 {
 	char const* text = R"(
 		contract C {
 			function f() {
-				(true ? 3 : 5) = 1;
+				uint x;
+				uint y;
+				(true ? x : y) = 1;
 			}
 		}
 	)";

Original file line number	Diff line number	Diff line change
`@@ -2972,12 +2972,14 @@ BOOST_AUTO_TEST_CASE(invalid_different_types_for_conditional_expression)`
`2972`	`2972`	`BOOST_CHECK(expectError(text) == Error::Type::TypeError);`
`2973`	`2973`	`}`
`2974`	`2974`
`2975`		`-BOOST_AUTO_TEST_CASE(invalid_left_value_in_conditional_expression)`
	`2975`	`+BOOST_AUTO_TEST_CASE(left_value_in_conditional_expression_not_supported_yet)`
`2976`	`2976`	`{`
`2977`	`2977`	`char const* text = R"(`
`2978`	`2978`	`contract C {`
`2979`	`2979`	`function f() {`
`2980`		`- (true ? 3 : 5) = 1;`
	`2980`	`+ uint x;`
	`2981`	`+ uint y;`
	`2982`	`+ (true ? x : y) = 1;`
`2981`	`2983`	`}`
`2982`	`2984`	`}`
`2983`	`2985`	`)";`